//! R46 — calibrated escalation gate.
//!
//! Closes the load-bearing correctness gap the 5-lens cross-talk audit
//! AND the May-31 strategy doc both named: *"the cascade is silent on
//! how a tier knows it failed."* Now the runtime consults an
//! `EscalationFn` after every synthesis-class tier answer:
//!
//!  - hook returns `true` ⇒ accept the tier's answer (legacy behaviour)
//!  - hook returns `false` ⇒ escalate (treat as `LowConfidence` refusal,
//!    walk to the next tier; the tier's joules still charge against the
//!    budget — the work was done)
//!
//! Deterministic tiers (`Cache | Lawful | Embed`) are NEVER gated —
//! their correctness is structural, not stochastic.

use jouleclaw_cascade::*;
use std::sync::atomic::{AtomicU32, Ordering};
use std::sync::Arc;
use std::time::Duration;

// ─────────────────────────────────────────────────────────────────────
// Mock tiers
// ─────────────────────────────────────────────────────────────────────

struct MockL3 {
    cost_joules: f64,
    confidence: f32,
    answer_text: String,
    calls: Arc<AtomicU32>,
}

impl MockL3 {
    fn new(cost: f64, conf: f32, text: impl Into<String>, calls: Arc<AtomicU32>) -> Self {
        Self {
            cost_joules: cost,
            confidence: conf,
            answer_text: text.into(),
            calls,
        }
    }
}

impl Tier for MockL3 {
    fn id(&self) -> TierId {
        TierId::L3(L3ModelId(0))
    }

    fn estimate_cost(&self, _q: &Query) -> Option<TierEstimate> {
        Some(TierEstimate {
            joules: self.cost_joules,
            latency: Duration::from_millis(40),
            confidence_floor: self.confidence,
        })
    }

    fn try_answer(&mut self, _q: &Query, _budget: f64) -> Result<Answer, AnswerError> {
        self.calls.fetch_add(1, Ordering::SeqCst);
        Ok(Answer {
            output: AnswerOutput::Text(self.answer_text.clone()),
            tier_used: self.id(),
            joules_spent: self.cost_joules,
            confidence: self.confidence,
            trace: ExecutionTrace::default(),
            verification: jouleclaw_cascade::verification::VerificationStatus::Resolved,
        })
    }
}

struct MockL4 {
    cost_joules: f64,
    confidence: f32,
    answer_text: String,
    calls: Arc<AtomicU32>,
}

impl MockL4 {
    fn new(cost: f64, conf: f32, text: impl Into<String>, calls: Arc<AtomicU32>) -> Self {
        Self {
            cost_joules: cost,
            confidence: conf,
            answer_text: text.into(),
            calls,
        }
    }
}

impl Tier for MockL4 {
    fn id(&self) -> TierId {
        TierId::L4(L4ModelId(0))
    }
    fn estimate_cost(&self, _q: &Query) -> Option<TierEstimate> {
        Some(TierEstimate {
            joules: self.cost_joules,
            latency: Duration::from_millis(100),
            confidence_floor: self.confidence,
        })
    }
    fn try_answer(&mut self, _q: &Query, _budget: f64) -> Result<Answer, AnswerError> {
        self.calls.fetch_add(1, Ordering::SeqCst);
        Ok(Answer {
            output: AnswerOutput::Text(self.answer_text.clone()),
            tier_used: self.id(),
            joules_spent: self.cost_joules,
            confidence: self.confidence,
            trace: ExecutionTrace::default(),
            verification: jouleclaw_cascade::verification::VerificationStatus::Resolved,
        })
    }
}

fn make_query(text: &str) -> Query {
    Query {
        input: QueryInput::Text(text.to_string()),
        budget: JouleBudget::expensive(),
        quality: QualityFloor::any(),
        context: ContextRef::fresh(),
        deadline: None,
    }
}

// ─────────────────────────────────────────────────────────────────────
// Tests
// ─────────────────────────────────────────────────────────────────────

#[test]
fn without_hook_legacy_behaviour_first_non_refused_wins() {
    let l3_calls = Arc::new(AtomicU32::new(0));
    let l4_calls = Arc::new(AtomicU32::new(0));
    let mut cascade = Cascade::new();
    cascade.register(Box::new(MockL3::new(0.5, 0.4, "L3 said", l3_calls.clone())));
    cascade.register(Box::new(MockL4::new(2.0, 0.9, "L4 said", l4_calls.clone())));
    // NB: no escalation hook installed.
    let mut runtime = Runtime::new(cascade);
    let answer = runtime.answer(make_query("test")).unwrap();
    // Without the gate, the L3 answer (confidence 0.4) wins despite
    // being low-confidence — the legacy behaviour.
    assert_eq!(answer.tier_used, TierId::L3(L3ModelId(0)));
    assert_eq!(l3_calls.load(Ordering::SeqCst), 1);
    assert_eq!(l4_calls.load(Ordering::SeqCst), 0);
}

#[test]
fn hook_rejects_low_confidence_l3_and_walk_continues_to_l4() {
    let l3_calls = Arc::new(AtomicU32::new(0));
    let l4_calls = Arc::new(AtomicU32::new(0));
    let mut cascade = Cascade::new();
    cascade.register(Box::new(MockL3::new(0.5, 0.4, "L3 low", l3_calls.clone())));
    cascade.register(Box::new(MockL4::new(2.0, 0.95, "L4 high", l4_calls.clone())));
    let mut runtime = Runtime::new(cascade)
        // Simple threshold: accept iff confidence >= 0.85.
        .with_escalation_hook(Box::new(|c: f32| c >= 0.85));
    let answer = runtime.answer(make_query("test")).unwrap();
    // L3 refused (0.4 < 0.85), walked to L4 which passes (0.95 >= 0.85).
    assert_eq!(answer.tier_used, TierId::L4(L4ModelId(0)));
    assert_eq!(l3_calls.load(Ordering::SeqCst), 1);
    assert_eq!(l4_calls.load(Ordering::SeqCst), 1);
    // L3's joules still charged to the spent total (the work happened).
    assert!(answer.joules_spent >= 0.5 + 2.0 - 1e-9);
}

#[test]
fn hook_accepts_high_confidence_answer_and_stops_walk() {
    let l3_calls = Arc::new(AtomicU32::new(0));
    let l4_calls = Arc::new(AtomicU32::new(0));
    let mut cascade = Cascade::new();
    cascade.register(Box::new(MockL3::new(0.5, 0.95, "L3 high", l3_calls.clone())));
    cascade.register(Box::new(MockL4::new(2.0, 0.99, "L4", l4_calls.clone())));
    let mut runtime =
        Runtime::new(cascade).with_escalation_hook(Box::new(|c: f32| c >= 0.85));
    let answer = runtime.answer(make_query("test")).unwrap();
    assert_eq!(answer.tier_used, TierId::L3(L3ModelId(0)));
    assert_eq!(l3_calls.load(Ordering::SeqCst), 1);
    assert_eq!(l4_calls.load(Ordering::SeqCst), 0); // L4 never touched
}

#[test]
fn refused_walk_records_low_confidence_in_the_trace() {
    let l3_calls = Arc::new(AtomicU32::new(0));
    let l4_calls = Arc::new(AtomicU32::new(0));
    let mut cascade = Cascade::new();
    cascade.register(Box::new(MockL3::new(0.5, 0.30, "L3", l3_calls.clone())));
    cascade.register(Box::new(MockL4::new(2.0, 0.99, "L4", l4_calls.clone())));
    let mut runtime =
        Runtime::new(cascade).with_escalation_hook(Box::new(|c: f32| c >= 0.85));
    let answer = runtime.answer(make_query("test")).unwrap();
    // Find the L3 entry in the trace — it must record a Refused
    // outcome with LowConfidence as the reason.
    let l3_entry = answer
        .trace
        .attempts
        .iter()
        .find(|e| e.tier == TierId::L3(L3ModelId(0)))
        .expect("L3 trace entry");
    match &l3_entry.outcome {
        TraceOutcome::Refused(RefusalReason::LowConfidence(_)) => (),
        other => panic!("expected Refused(LowConfidence), got {:?}", other),
    }
    // L3's joules still recorded in the trace (the work was done).
    assert!(l3_entry.joules > 0.0);
}

#[test]
fn hook_does_not_gate_l0_cache_hits() {
    // L0 cache is gated only by tier type, not confidence; if a cache
    // hit returned with low confidence, the gate must NOT fire because
    // cache correctness is structural.
    //
    // We exercise this via the no-L0 runtime so the test is hermetic
    // (no auto-cache to interfere), but the assertion holds at the
    // joule_class level: only Model | Wire are gated.
    let l3_calls = Arc::new(AtomicU32::new(0));
    let mut cascade = Cascade::new();
    cascade.register(Box::new(MockL3::new(0.5, 0.4, "L3", l3_calls.clone())));
    let mut runtime = Runtime::new_without_l0(cascade)
        // A hook that ALWAYS rejects. If applied to L3, L3's answer is
        // refused and the walk runs out of tiers.
        .with_escalation_hook(Box::new(|_c: f32| false));
    let result = runtime.answer(make_query("test"));
    // Out of tiers after the L3 refusal — the cascade should surface a
    // NoApplicableTier error or similar. Verifies the hook DID fire on
    // L3 (confirming gating on Model class).
    assert!(result.is_err(), "expected error when hook rejects all tiers");
}

#[test]
fn has_escalation_hook_reports_install_state() {
    let cascade = Cascade::new();
    let runtime = Runtime::new(cascade);
    assert!(!runtime.has_escalation_hook());
    let cascade = Cascade::new();
    let runtime = Runtime::new(cascade).with_escalation_hook(Box::new(|_| true));
    assert!(runtime.has_escalation_hook());
}